The present invention relates generally to utilization of crankcase vapors in internal combustion engines, and more particularly to an improved automotive fuel saving system which utilizes such vapors.
Existing systems for circulating crankcase vapors into the air and fuel intake system of an internal combustion engine include that described in U.S. Pat. No. 3,677,240 to Sarto, as well as those of U.S. Pat. No. 1,286,930 to Buckner and U.S. Pat. No. 1,299,790 to Scott. Background material and descriptions of these and other known systems are given in U.S. Pat. No. 4,279,236 (hereinafter "the '236 system") and U.S. Pat. No. 4,404,950 (hereinafter "the '950 system") to the present inventor, the background and teachings of which patents are incorporated herein by reference.
Crankcase vapors generated in the operation of an internal combustion engine comprise two major components, viz., blowby gases including a carbureted mixture plus exhaust gases passing by the piston rings and entrained particles and other matter of the crankcase lubricating oils which are vaporized by engine heat and agitation. The blowby gases contain water vapor and include large amounts of hydrocarbons and carbon monoxide having high fuel content. Vaporized crankcase lubricating oil often contains relatively large and heavy particulates which are not readily combustible in the engine considering the extremely short burn time for fuel within a cylinder.
The '236 system includes three air flow circuits for handling crankcase vapors. In a first air flow circuit, ram air captured by an air scoop and cooperating with an aspirator draws crankcase vapors from the crankcase and conducts them to the carburetor of the engine. Heavy particulate matter in the vapors is separated, heated and vaporized in a portion of the first circuit disposed in heat exchange relationship with an exhaust manifold of the engine. A second aspirator in the first circuit draws vaporized particulate matter into the first circuit. Vapors mixed with incoming ram air are then directed into the carburetor through the air cleaner cover. A second circuit feeds ventilation air captured by another air scoop into the crankcase and carburetor air cleaner cover to achieve continuous circulation of air through the crankcase and ventilation of vapor therefrom. The '950 system improved on the '236 system by including a belt driven air pump replacing the air scoops of the '236 system. A third air flow circuit in each system adds air to the carburetor to avoid an overly rich fuel/air mixture in the caburetor. The '236 and '950 systems demonstrated improved fuel economy and large reduction in emissions of hydrocarbons (HC) and carbon monoxide (CO). However, characteristics of bleed air type systems, the '236 and '950 systems were characterized by undesirable increase in nitrogen oxides (NO.sub.x) emissions.
The present invention provides a substantially improved system for withdrawing vapor from the crankcase of an internal combustion engine, expanding and cooling the vapor to an aerosol state, and inserting the aerosol in to the carburetor of the engine. The aerosol is inserted at any region of the carburetor where a vacuum is generated or maintained, such as at the crankcase ventilation (CV) port, to improve performance and fuel efficiency of the engine. The insertion of crankcase vapors as aerosols into the engine may slow the burn rate of fuel in the cylinders and correspondingly effectively increase the octane rating of the fuel. Tests on a demonstration system indicated at 10-15% increase in fuel economy, improved engine performance and substantial reduction in hydrocarbon, CO and NO.sub.x engine exhaust emissions are compared to the engine without the improvement of the invention.
In accordance with the invention, a first vapor flow circuit interconnects the valve cover, such as at the crankcase vapor port, and the carburetor, such as at the CV vapor port on the carburetor below the throttle plate, to aspirate vapor from the crankcase at high manifold vacuum levels associated with engine operation at medium throttle to curb idle conditions; the first circuit includes means to expand and cool the vapor to an aerosol state prior to insertion into the carburetor which means may comprise an orifice and expansion chamber. A second vapor flow circuit connects the valve cover with the air cleaner cover to promote vapor flow from the valve cover at low to zero manifold vacuum associated with engine operation at medium to wide open throttle conditions. In certain fuel/air supply systems, a vacuum is maintained at substantially all throttle conditions which can be utilized by the invention to draw vapor from the crankcase at all engine operating conditions; for these systems no second circuit is required. No forced air circulation through the system is required.
The discussion herein presented emphasizes the utilization of the invention on gasoline powered, spark ignition engines, which engine type was used in demonstration of the invention. It is asserted, however, that the invention is applicable to other engine types, such as a Diesel, by modification of the invention by one with skill in the field of the invention guided by these teachings.
It is, therefore, a principal object of the invention to provide a system for fuel efficient utilization of crankcase vapors in an internal combustion engine.
It is a further object of the invention to provide an improved fuel efficient fuel/air supply system for an internal combustion engine.
It is yet a further object of the invention to provide a fuel efficient internal combustion engine.
It is yet another object of the invention to provide a system for fuel efficient utilization of crankcase vapors in a fuel injected internal combustion, spark ignition gasoline engine.
It is another object of the invention to provide an improved full scale fuel efficient carburetion system for an internal combustion, spark ignition gasoline engine.
These and other objects of the invention will become apparent as the description of representative embodiments proceeds.